I agree with my fellow DM there. I've played through part of the game and only gotten 2 kinds before and played through again and gotten 5-7 different ones. Like DarthMoeller said make sure to check all loot stuff. Some are actually scripted into certain containers and such so they are there every time.
I even know of one party member if talked to right will "give" you on of the former Sith Lord lightsabers